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United States Patent |
5,243,386
|
Araki
,   et al.
|
September 7, 1993
|
Optical system housing structure for image forming apparatus
Abstract
An image forming apparatus such as an electrophotographic copying machine
includes an optical system for housing a scanning exposure optical system.
The optical system housing has air inlet and outlet holes for introducing
air into and discharging air from the optical system housing. The air
outlet holes have an opening area greater than an opening area of the air
inlet holes. Electrostatic filters are mounted on the optical system
housing in covering relation to the air inlet and outlet holes. Thus, the
optical system housing is substantially closed. The optical system housing
is composed of surrounding walls having ends joined in pairs in
interdigitating relationship, one of the ends in each of the pairs having
an end surface held in abutment against an inner surface of the
surrounding wall having the other end. An image forming mechanism is
housed in an image forming mechanism housing having a pair of confronting
side walls spaced from each other. One of the side walls is taller than
the other side wall, and has support fingers projecting laterally from an
inner surface. The optical system housing is supported on the support
fingers and the other side wall.
Inventors:
|
Araki; Takahisa (Utsunomiya, JP);
Nakayama; Yoshihiro (Utsunomiya, JP);
Sasai; Kinya (Utsunomiya, JP)
|
Assignee:
|
Matsushita Electric Industrial Co., Ltd. (Osaka, JP)
|
Appl. No.:
|
686979 |
Filed:
|
April 18, 1991 |
Foreign Application Priority Data
| Apr 19, 1990[JP] | 2-103918 |
| May 22, 1990[JP] | 2-132240 |
| May 22, 1990[JP] | 2-132241 |
Current U.S. Class: |
399/93; 399/95 |
Intern'l Class: |
G03G 015/04 |
Field of Search: |
355/215,233,200,210,235,133,30
174/50,52.1
361/390,429
|
References Cited
U.S. Patent Documents
3386606 | Jun., 1968 | Pastrick | 174/50.
|
3564112 | Feb., 1971 | Algotsson | 361/356.
|
4198156 | Apr., 1980 | Barker et al. | 355/30.
|
4286861 | Sep., 1981 | Matsumoto | 355/215.
|
4647178 | Mar., 1987 | Sasaki et al. | 355/200.
|
4695151 | Sep., 1987 | Watanabe | 355/30.
|
4847643 | Jul., 1989 | Ohmori | 355/233.
|
4912563 | Mar., 1990 | Narita | 355/200.
|
4931836 | Jun., 1990 | Matsushita et al. | 355/233.
|
5073796 | Dec., 1991 | Suzuki et al. | 355/215.
|
Foreign Patent Documents |
0153824 | Sep., 1985 | EP.
| |
0269131 | Jun., 1988 | EP.
| |
54-31740 | Aug., 1979 | JP.
| |
0017957 | Jan., 1982 | JP | 355/215.
|
0200070 | Dec., 1982 | JP | 355/215.
|
62-10423 | Mar., 1987 | JP.
| |
62-296166 | Dec., 1987 | JP.
| |
63-199376 | Aug., 1988 | JP.
| |
Primary Examiner: Grimley; A. T.
Assistant Examiner: Beatty; Robert
Attorney, Agent or Firm: Lowe, Price, LeBlanc & Becker
Claims
What is claimed is:
1. An optical system housing structure for use in an image forming
apparatus, comprising:
an optical system housing for housing a scanning exposure optical system;
said optical system housing having air inlet and outlet holes defined
therein, said air inlet and outlet holes providing communication between
the outer atmosphere and an interior of said optical system housing, said
air outlet holes having an opening area greater than an opening area of
said air inlet holes;
electrostatic filters mounted on said optical system housing in fully
covering relation to said air inlet and outlet holes, for filtering the
air to e introduced into said optical system housing through said air
inlet holes at all times, whereby said optical system housing with said
electrostatic filters form a substantially closed structure; and
a lamp of said scanning exposure optical system mounted in said optical
system housing and positionable in a home position before the scanning
exposure optical system starts to operate, whereby said air inlet holes
are arranged in said optical system housing near said home position to
improve cooling efficiency of the scanning exposure optical system.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical system housing structure for
use in an electrophotographic image forming apparatus such as a
photocopying machine.
2. Prior Art
Electrophotographic image forming apparatus such as photocopying machines,
laser beam printers, or the like are widely used in offices and other
applications. As disclosed in Japanese Patent Publication No. 62-10423,
most of such electrophotographic image forming apparatus have a housing
structure which comprises a housing that contains an image forming
mechanism including a photosensitive body and another housing that
accommodates a scanning exposure optical system for optically scanning a
subject and exposing the photosensitive body to an optical image of the
subject. The housing which houses the scanning exposure optical system is
placed on and fixed to the housing which houses the image forming
mechanism. These housings are basically optically independent of, or
isolated from, each other so that no light from a light source for
applying scanning light to the subject in the exposure optical system will
directly fall on the photosensitive body, thus preventing noise from being
included in the final image. The independent housings can be installed and
removed separately from each other.
The housing which houses the scanning exposure optical system, hereinafter
referred to as the "optical system housing", including a glass platen for
supporting the subject on its upper surface, tends to be heated to high
temperature, making the user feel anxious about the condition of the
scanning exposure optical system or sometimes making the user feel hot.
Heretofore, external air is introduced into the optical system housing to
cool the internal scanning exposure optical system and the glass platen so
that they will not be unduly heated. The cooling air is forcibly delivered
into the optical system housing by a fan. The optical system housing has
an air inlet for introducing the cooling air and an air outlet for
discharging the air after it has cooled the scanning exposure optical
system and the glass platen. The air inlet is equipped with a filter for
preventing dust from entering the optical system housing through the air
inlet. The air outlet is usually left open without any filter.
It is known that the quality of images produced by the image forming
apparatus is gradually degraded with time. The experience of the inventors
indicates that the timedependent image quality deterioration takes place
irrespectively of whether the image forming apparatus has been used
frequently or not, and is caused due primarily to dust applied to optical
surfaces of some optical components, such as mirrors, of the scanning
exposure optical system. Small dust particles, which are invisible to
human eyes, are suspended in air continuously for a long period of time,
flow through narrow gaps, and are attached to the optical components. Even
though those dust particles are small in size, they bring about a loss of
light intensity when deposited to a certain thickness.
It is necessary that the optical components of the scanning exposure
optical system be supported such that they can move for the scanning of
the subject while remaining parallel to each other and to the
photosensitive body or being kept at suitable distances from each other
and from the photosensitive body. If the optical components are not
properly held parallel to, or spaced from, each other and the
photosensitive body, then the sharpness of generated images is gradually
lowered, resulting in a image quality reduction. The optical system
housing comprises surrounding side walls simply put together and joined
together by arc welding. These surrounding side walls themselves do not
have any means for keeping them perpendicularly to each other and also to
a bottom panel. Therefore, certain jigs are necessary to position the side
walls in order to hold them perpendicularly to each other and to the
bottom panel when the side walls are joined together. The cost of the
optical system housing thus constructed is relatively high because the
side walls and the bottom panel are assembled using many jigs and the
assembling procedure is complex. The complex assembling procedure is
liable to impair the perpendicularity to be achieved between the walls.
When the assembled walls are joined by arc welding, the desired
perpendicularity may be lost due to the thermal strain of the walls. After
the optical system housing has been assembled and welded, it has to be
adjusted or finished for desired perpendicularity. The finishing process
is tedious and time-consuming, and adds to an increase in the cost.
The various components are housed in the housings in accurate positions and
with accurate attitudes. Unless the housings are coupled to each other in
an accurate position and with an accurate attitude, however, the optical
images cannot be formed on the photosensitive body by the scanning
exposure optical system.
It is highly difficult to accurately align the upper edges of side walls of
the housing which houses the image forming mechanism, hereinafter referred
to as the "image forming mechanism housing", for supporting the optical
system housing.
Heretofore, the optical system housing is fixedly mounted on the image
forming mechanism housing after the upper edges of the side walls of the
image forming mechanism housing have been adjusted in height.
However, a complicated position adjusting process is required to adjust the
upper edges of the side walls of the image forming mechanism housing, and
hence the housings cannot easily be assembled together. No positional
reference is provided by either the image forming mechanism housing or the
optical system housing when the upper edges of the side walls of the image
forming mechanism housing are adjusted in height. After the adjusting
process, the optical system housing is positionally adjusted back and
forth and laterally on the image forming mechanism housing, and then the
housings are joined to each other while being maintained in proper
relative positions. Accordingly, it requires skill and time to assemble
and join the housings, and the overall assembling and joining process is
relatively costly.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optical system
housing structure for image forming apparatus which will solve the
problems of the conventional optical system housing structure, the optical
system housing structure being substantially closed but allowing
ventilation for cooling a scanning exposure optical system and a glass
platen.
Another object of the present invention is to provide an optical system
housing structure whose surrounding walls can easily be joined, without
using jigs, for desired perpendicularity therebetween.
Still another object of the present invention is to provide an optical
system housing structure including an image forming mechanism housing and
an optical system housing, the image forming mechanism housing being of an
improved structure for supporting the optical system housing thereon.
According to the present invention, there is provided an optical system
housing structure for use in an image forming apparatus, comprising an
optical system housing for housing a scanning exposure optical system, the
optical system housing having air inlet and outlet holes defined therein
for introducing air into and discharging air from the optical system
housing, and electrostatic filters mounted on the optical system housing
in covering relation to the air inlet and outlet holes, for filtering the
air to be introduced into the optical system housing through the air inlet
hole, whereby the optical system housing being substantially closed.
The optical system housing is composed of surrounding walls having ends
joined in pairs in interdigitating relationship, one of the ends in each
of the pairs having an end surface held in abutment against an inner
surface of the surrounding wall having the other end.
An image forming mechanism housing for housing an image forming mechanism
has a pair of confronting side walls spaced from each other, one of the
side walls being taller than the other side wall, and having support
fingers projecting laterally from an inner surface thereof. The optical
system housing being supported on the support fingers and the other side
wall.
The above and other objects, features and advantages of the present
invention will become more apparent from the following description when
taken in conjunction with the accompanying drawings in which a preferred
embodiment of the present invention is shown by way of illustrative
example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a vertical cross sectional view of a photocopying machine which
has an optical system housing structure according to the present
invention;
FIG. 2 is an exploded perspective view of an optical system housing;
FIG. 3 is an exploded perspective view showing the manner in which the
optical system housing is assembled; and
FIG. 4 is a perspective view of an image forming mechanism housing on which
the optical system housing is to be placed.
DETAILED DESCRIPTION
FIG. 1 shows in vertical cross section an electrophotographic photocopying
machine as an image forming apparatus which has an optical system housing
structure according to the present invention. The photocopying machine
comprises a scanning exposure optical system 1, an image forming mechanism
3 for producing an image through exposure by the scanning exposure optical
system 1 and transferring the image to an image transfer sheet 2, and a
sheet feed mechanism 4 for feeding an image transfer sheet 2 to the image
forming mechanism 3. The scanning exposure optical system 1, the image
forming mechanism 3, and the sheet feed mechanism 4 are housed
respectively in an optical system housing 6, an image forming mechanism
housing 7, and a sheet feed mechanism housing 8, which are independent of
each other. The optical system housing 6 is placed on the image forming
mechanism housing 7 which is positioned on the sheet feed mechanism
housing 8. These housings 6, 7, 8 which are thus stacked is coupled
together, thus providing a machine frame 9.
The scanning exposure optical system 1 has a lamp 13 for applying scanning
line to a subject (not shown) on a glass platen 11, the lamp 13 being
supported on a first slider 12 movable below the glass platen 11. Light
reflected from the subject on the glass platen 11 is reflected by a first
mirror 14 supported on the first slider 13. A second slider 15 is also
movable below the glass platen 11 and supports second and third mirrors
17, 18. Fourth and fifth mirrors 19, 20 are supported on a third slider 16
movably disposed below the glass platen 11. The second through fifth
mirrors 17 through 20 serve to keep a constant optical path for the light
reflected from the first mirror 14. The scanning exposure optical system 1
also has a projection lens 21 disposed between the third and fourth
mirrors 18, 19. A sixth mirror 22 disposed near the fifth mirror 20 serves
to correct the length of the optical axis when the magnification is varied
by movement of the projection lens 21 along its optical axis.
The image forming mechanism 3 comprises a photosensitive drum 31, a
charging charger 32, an image developing unit 33, a transfer charger 32, a
separation charger 135, and a cleaning unit 136, which are successively
disposed around the photosensitive drum 31. The image forming mechanism 32
operates according to the known electrophotographic process, i.e., forms a
toner image on the photosensitive drum 31 based on an electrostatic latent
image formed thereon, and transfers the toner image onto a transfer sheet
2 supplied to the photosensitive drum 31.
A sheet feed path 35 extends from the sheet feed mechanism 4 to an image
transfer region where the photosensitive drum 31 and the transfer charger
34 confront each other. The sheet feed path 35 serves to supply a transfer
sheet 2 from the sheet feed mechanism to the image transfer region. The
sheet feed path 35 has a pair of timing rollers 36. When the timing
rollers 36 are at rest, a transfer sheet 2 is fed to the timing rollers
36, and has its leading edge aligned thereby so that the transfer sheet 2
is corrected out of any skewed condition. Then, the timing rollers 36 are
rotated to feed the transfer sheet 2 to the image transfer region.
Therefore, the timing to supply the transfer sheet 2 to the image transfer
region can be adjusted by the timing rollers 36.
The image forming mechanism 3 further includes a feed unit 37 comprising a
feed belt for attracting and feeding the transfer sheet 2 onto which the
toner image has been transferred. The toner image on the transfer sheet 2
is then fixed by a fixing unit 38. The transfer sheet 2 from the fixing
unit 38 is discharged by discharge rollers 39.
The sheet feed mechanism 4 comprises three sheet feeders 41, 42, 43 storing
transfer sheets 2 of different sizes. The transfer sheets 2 of different
sizes are selectively fed from the sheet feeders 41, 42, 43 to the image
forming mechanism 3 through the sheet feed path 35. The sheet feeders 41,
42, 43 have respective sheet cassettes 44, 45, 46 for storing transfer
sheets, respective pickup rollers 47, 48, 49 for delivering transfer
sheets from within the sheet cassettes 44, 45, 46, and respective
separator pads 50 for separating the transfer sheets from each other so
that they will be fed one at a time. The sheet feeders 41, 42, 43 are
unitized as blocks, which can be replaced with other blocks. For example,
two sheet feeders may be replaced with one sheet feeder which stores a
greater number of sheets. The sheet cassettes 41, 42, 43 may be loaded and
unloaded through a front panel of the machine frame 9, i.e., in directions
toward and away from the viewer of FIG. 1.
As better shown in FIG. 2, the optical system housing 6 has air inlet holes
52 defined in a rear wall 51, and air outlet holes 55, 56 defined in
lateral side walls 53, 54. An air blower fan 57 is mounted on the outside
of the rear wall 51 over the air inlet holes 52, for introducing external
air into the optical system housing 6 and discharging air from the optical
system housing 6 through the air outlet holes 55, 56. When the air blower
fan 57 is actuated, air flows as indicated by the arrows in FIG. 2, thus
cooling the interior of the optical system housing 6. Therefore, even when
the lamp 13 is heated, the glass platen 11 is prevented from being unduly
heated, so that the operator will not feel anxious or hot. The air inlet
holes 52 are positioned near the lamp 13 as it is in a home position
before the scanning exposure optical system 1 starts to operate.
Accordingly, the region in the optical system housing 6 where the lamp 13
is positioned more often and the temperature is higher, is effectively
cooled by the cooling air introduced through the air inlet holes 52. Thus,
the cooling efficiency of the scanning exposure optical system 1 is high.
The machine frame 9 is covered with a resin cover 58 which has air
ventilation holes 59 (FIG. 1) defined therein in registry with the air
inlet and outlet holes 52, 55, 56 for allowing air to be introduced into
and discharged out of the optical system housing 6.
The interior of the optical system housing 6 may be cooled by air which is
drawn into and discharged out of the optical system housing 6 under
suction.
Since the interior of the optical system housing 6 is vent to atmosphere
through the air inlet holes 52 and the air outlet holes 55, 56, dust would
be introduced into the optical system housing 6, and deposited on the
reflecting surfaces of the mirrors of the scanning exposure optical system
14, lowering the quality of the final images on transfer sheets 2.
Particularly, small invisible dust particles which are suspended in air
over a long period of time would enter the optical system housing 6
irrespective of whether the photocopying machine is used or not, impairing
the scanning exposure optical system 1.
To avoid deposition of such small dust particles on the components of the
scanning exposure optical system 1, electrostatic filters 61, 62 are
disposed at the air inlet and outlet holes 52, 55, 56 for trapping small
dust particles under electrostatic attractive forces. The electrostatic
filters 61, 62 may be of a known nature disclosed in Japanese Patent No.
1102749, and are manufactured by Sumitomo 3M Co., Ltd. and Toyobo Co.,
Ltd.
The filter 61 is mounted over an air inlet port 162 of the air blower fan
57. The air blower fan 57 has guide slots 63 in which ends of the filter
62 are inserted. The filter 61 is fastened to the air blower fan 57 by
screws 64. The filters 62 are disposed over the air outlet holes 55, 56
with positioning teeth engaging in corresponding slots in the side walls
of the optical system housing 6, and are fastened to the sides walls 53,
54 by screws 65.
The air inlet holes 52 are relatively small because cooling air is forcibly
introduced therethrough by the air blower fan 57 and should be applied
intensively to the lamp 13 as it is in the home position. On the other
hand, the air outlet holes 55, 56 are relatively large in order to cause
cooling air to be dispersed in the optical system housing 6 and smoothly
discharged from the optical system housing 6.
The total opening area of the air outlet holes 55, 56 is much larger than
the total opening area of the air inlet holes 52. Accordingly, air flows
through the air inlet holes 52 at a speed much higher than the speed at
which air flows through the air outlet holes 55, 56. The electrostatic
filters 61, 62 are constructed to induce different pressure losses with
respect to such different air flow speeds in order to allow the cooling
air to well cool the interior of the optical system housing 6 and also to
cause the electrostatic filters 61, 62 to well trap dust particles
regardless of the difference between the air flow speeds.
An experiment was conducted on an optical system housing of the above
structure with the filter 61 made of DEL-20 manufactured by Sumitomo 3M
Co., Ltd., and the filters 62 made of Type A, 100 g/m.sup.2 manufactured
by Toyobo Co., Ltd. The results of the experiment are as follows:
TABLE 1
______________________________________
Dust collection efficiency
(0.5.about.1 .mu.m) E
Air flow speed
Air flow speed
in the air outlet
in the air inlet
holes: 20 cm/s
holes: 100 cm/s
______________________________________
DEL-20 28% 17%
(Sumitomo 3M)
Type A, 100 g/m.sup.2
36% 5%
(Toyobo)
______________________________________
TABLE 2
______________________________________
Pressure loss .DELTA. P
Air flow speed
Air flow speed
in the air outlet
in the air inlet
holes: 20 cm/s
holes: 100 cm/s
______________________________________
DEL-20 0.2 mm H2O 1.9 mm H2O
(Sumitomo 3M)
Type A, 100 g/m.sup.2
0.4 mm H2O 3.4 mm H2O
(Toyobo)
______________________________________
As seen from Tables 1 and 2, the electrostatic filter of Sumitomo 3M in the
air inlet port 162 was better with respect to the dust collection
efficiency and the pressure loss, and the electrostatic filters 62 of
Toyobo in the air outlet holes 55, 56 were better with respect to the dust
collection efficiency.
The electrostatic filters of Sumitomo 3M and Toyobo were satisfactory with
respect to cooling and dust removal capabilities. The electrostatic
filters of Sumitomo 3M were effective for use in both the air inlet port
162 and the air outlet holes 55, 56.
As shown in FIGS. 1 and 3, the first slider 12 and the second slider 15 are
guided by longitudinal guide bars 60, 61 extending between and attached to
the side walls 53, 54, and the third slider 16 is guided by a guide rail
63 mounted on a bottom panel 62 of the optical system housing 6. The first
through fifth mirrors 14, 17 through 20, which are supported on the first,
second, and third sliders 12, 15, 16, should be held parallel to each
other and also to the circumferential surface of the photosensitive drum
31 and should be spaced at given distances from each other and also from
the circumferential surface of the photosensitive drum 31.
According to the illustrated embodiment of the present invention, the side
walls 53, 54, the rear wall 51, and a front wall 64 of the optical system
housing 6 are held well perpendicularly to each other, and also to the
bottom panel 62, and the optical system housing 6 is placed on and fixed
to the image forming mechanism housing 7 in an accurate position and with
an accurate attitude.
More specifically, as shown in FIG. 3, the front wall 64 is integral with
and bent upwardly from a front edge of the bottom panel 62. The side walls
53, 54 and the rear wall 51 are separate from the bottom panel 62 and
hence the front wall 64. Each of the bottom panel 62, the side walls 53,
54, and the rear wall 51 is produced by blanking a metal sheet to a
desired shape, and bending the blank to a final three-dimensional shape.
The edges of the bottom panel 62, the side walls 53, 54, the rear wall 51,
and the front wall 64 thus blanked are high in dimensional and positional
accuracy.
The confronting ends of the walls 51, 53, 54, 64 are held in abutment
against each other to position these walls relatively to each other, and
each have alternate recesses 71 and positioning ridges 72. When the
confronting ends of the walls 51, 53, 54, 64 abut against each other, the
positioning ridges 72 are received and locked in the respective recesses
71 in interdigitating relationship as indicated by the solid- and
broken-line arrows. Recessed surfaces of one end of one of the walls are
held in abutment against the inner surface of another wall at its end. The
confronting ends thus combined with each other are prevented from being
vertically displaced in position by the ridges 72 locked in the recesses
71. In addition, the walls 51, 53, 54, 64 are held perpendicularly to each
other and also to the bottom panel 62 by the abutting engagement between
the confronting ends of the walls 51, 53, 54, 64 because the abutting ends
are high in dimensional and positional accuracy.
Since accurate perpendicularity is obtained between the adjacent ones of
the walls 51, 53, 54, 64, and also between the walls 51, 53, 54, 64 and
the bottom panel 62. Therefore, the first through fifth mirrors 14, 17
through 20 which are supported in and guided with respect to the optical
system housing are accurately held parallel to each other and also to the
photosensitive drum 31 and spaced desired distances from each other and
also from the photosensitive drum 31. Accordingly, the subject on the
glass platen 11 can properly be scanned by the scanning exposure optical
system 1.
The confronting ends of the walls 51, 53, 54, 64 are joined together by
plasma welding, so that the perpendicularity between the walls 51, 53, 54,
64 and also between them and the bottom panel 62 is prevented from being
thermally affected. The optical system housing 6 that has been assembled
and welded is not required to be corrected or adjusted in angles between
the walls 51, 53, 54, 64 and also between them and the bottom panel 62.
In the illustrated embodiment, only the front wall 64 is integral with the
bottom panel 52. However, any one of the walls 51, 53, 54, 64 may be
integral with the bottom panel 62, or they may be independent of the
bottom panel 62. If more walls are integral with the bottom panel 62, then
the optical system housing 6 is made up of a smaller number of components
and can be assembled in a smaller number of steps, and the walls are
positionally related to the bottom panel more accurately.
The optical system housing 6 of the above structure is placed on and fixed
to the image forming mechanism housing 7, as shown in FIG. 4. The image
forming mechanism housing 7 comprises a bottom panel 81, drawn from a
metal sheet, and a pair of front and rear confronting side walls 82, 83,
each drawn from a metal sheet, mounted vertically on the bottom panel 81
in spaced relationship to each other. The side walls 82, 83 are fastened
to the bottom panel B1 by bolts and nuts (not shown). The side walls 82,
83 have positioning surfaces 84 projecting downwardly and held against the
bottom panel 81, so that the side walls 82, 83 can easily be positioned
relatively to the bottom panel 81. The bottom panel 81 and the side walls
82, 83 are thus coupled to each other in accurate relative positional
relationship.
The front side wall 82 is taller than the rear side wall 83. The taller
front side wall 82 has support fingers 85 pierced and raised with
accuracy. The front side wall 82 also has an inner surface above the
support fingers 85. One side of the optical system housing 6 is supported
on the support fingers 85, and an outer surface of the supported side is
held against the inner surface of the front side wall 82. The optical
system housing 6 is therefore transversely positioned in a proper position
and with a proper attitude easily by the inner surface of the front side
wall 82. The rear side wall 83 has raised positioning surfaces 86 on its
upper edge for supporting the opposite side of the optical system housing
6. By adjusting the height of the support fingers 85 and the positioning
surfaces 86, the optical system housing 6 is also positioned vertically on
the image forming mechanism housing 7 in a proper position and with a
proper attitude. The optical system housing 6 is fastened to the image
forming mechanism housing 7 by bolts and nuts 91.
The optical system housing 6 is easily placed on and fixed to the image
forming mechanism housing 7 in a proper position and with a proper
attitude, the first through fifth mirrors 14, 17 through 20 and the
photosensitive drum 31 are maintained suitably parallel to each other and
positioned appropriately relatively to each other. The high positional
accuracy achieved between the components in the scanning exposure optical
system 1 and the image forming mechanism 3 allows the image forming
apparatus to produce images of high quality.
The position, number, and shape of the support fingers 85 of the front side
wall 82 may be modified, and also the position, number, and shape of the
positioning surfaces 86 of the rear side wall 83. The optical system
housing 6 and the image forming mechanism housing 7 may be fastened to
each other by any suitable fastening means other than the bolts and nuts
91.
The optical system housing structure according to the present invention may
be incorporated in an image forming apparatus in which a scanning exposure
optical system is fixed in position and a subject to be copied is moved
over the scanning exposure optical system when the subject is scanned
thereby. Air inlet holes should be defined in a position corresponding to
the fixed scanning exposure optical system. The principles of the present
invention are applicable to other image forming apparatus with scanning
exposure optical systems which are heated in use.
Although a certain preferred embodiment has been shown and described, it
should be understood that many changes and modifications may be made
therein without departing from the scope of the appended claims.
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